Characterization of γ′ Precipitation Kinetics in Additively Manufactured Ni-Based Superalloy ABD®-900AM

Journal article

The γ′ precipitation behavior in additively manufactured ABD®-900AM is quantified in the temperature range of 700 K to 1200 K (427 °C to 927 °C). Data for γ′ precipitate size distributions and median radii are reported as a function of annealing time and temperature. An empirical model predicting the median γ′ precipitate size during post-build heat treatment is established, and effective diffusion coefficients are determined at the three studied temperatures. A strong correlation between median γ′ precipitate size and bulk hardness is identified, revealing an optimum precipitate size of 10 to 20 nm for maximum hardness and enabling classification of the precipitation process into two stages: γ → γ + γ′ transformation and subsequent coarsening. A time–temperature–transformation (TTT) diagram is constructed and further rationalized using CALPHAD and TC-PRISMA modeling. Notably, interconnected γ′ morphologies are observed at early reaction times (r < 6 nm), indicating the possible involvement of spinodal decomposition in the precipitation mechanism. The work provides comprehensive datasets for thermal stability, mechanical response, and phase evolution in ABD®-900AM and offers insights for post-processing strategies and predictive modeling in AM Ni-based superalloys.

Authors: Zhuge, Y; Tang, YT; McCartney, DG; Lozano-Perez, S; Reed, RC

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Springer
• Journal: Metallurgical and Materials Transactions A
• Pages: 1-15
• Publication date: 2026-01-09
• Acceptance date: 2025-12-10
• DOI: 10.1007/s11661-025-08081-z
• EISSN: 1543-1940
• ISSN: 1073-5623
• Language: English
• Keywords: Superalloy; Characterization (materials science); Microstructure; Annealing (glass); Precipitation; CALPHAD; Phase diagram; Spinodal decomposition